Methods and devices for a surgical hip replacement procedure

ABSTRACT

Devices and methods for use in a hip replacement surgical procedure. One aspect includes methods and devices for reaming selective regions of the femoral canal. This may include reaming distal and proximal sections of the femoral canal prior to reaming a middle region of the canal. Another aspect includes a dummy implant and methods of use. The dummy implant is inserted into the femoral canal and may be used for one or more of retraction of the femur, gauging a space with the acetabulum, and further revising the femoral cut. The aspects may be used together in a single surgical procedure or separately in different surgical procedures.

BACKGROUND

The present application is directed to hip replacement procedures and,more particularly, to methods and devices for preparing and sizing thefemur to receive a femoral component.

Hip replacement procedures involve the replacement of the hip jointformed by the head of the femur and the acetabulum of the pelvic bone.Hip replacement procedures include the preparation of the femur forreceipt of a first component and preparation of the acetabulum toreceive a second component. The two components engage together toreplace the hip joint. Numerous surgical approaches exist exposing thejoint to perform hip replacement surgeries.

Initially, the transtrochanteric approach was most popular, as advocatedby the father of hip replacement surgery, John Charnely. This involvedexposing the boney prominence to the side of the human hip, that isattached to the femur and to which the abductor muscles attach, tostabilize the hip/pelvis during gait. Over time, surgeons began goingeither in front of (anterior orientated approaches) or behind (posteriorbased approaches) the trochanter.

Anterior orientated approaches had many variations and names(Anteriolateral, Watson-Jones, direct lateral, Smith-Peterson, directanterior) many of which involved detaching the abductor muscle withoutremoving the trochanter. These approaches all shared a low postoperativehip dislocation rate. However, the most popular of these approachesanterior the trochanter had the drawback of longer recovery andpotentially weakened abductor muscle. Posterior orientated approacheswere less destructive to the abductor muscle, but with the disadvantageof a higher postoperative dislocation rate.

The ideal approach would have the advantages of approaches anterior tothe trochanter in regard to dislocation, without the disadvantages ofincreased muscle damage/recovery/weakness.

The damage to the soft tissue and muscles with anterior based approachesoccurs during the preparation of the femur for the femoral component.The use of cement to obtain implant fixation has largely been replacedby cementless (bone ingrowth) implant designs, that require theintra-medulary femoral canal to be reamed and/or rasped to an exactsilhouette of the final prosthetic implant. Reamer-based systems havethe advantage of accurately machining bone of varying density, similarto the accuracy of a drilling a pilot hole for a screw. The disadvantageof reamers is that occasionally more bone/soft tissue gets reamed thanintended. These elongated reamers include cutting edges that extendalong their length. The cutting edges extend outward beyond the canaland may contact against the nearby tissue during rotation of the reamer.This contact damages the tissue thus causing a more invasive procedurewith additional recovery time for the patient.

As muscle sparing approaches (anterior to the trochanter) havedeveloped, shorter stems that do not require bone preparation using fulllength straight reamers have been introduced. Techniques that requirespecific untested implant designs are at risk for unforeseencomplications. For rasp prepared short stem implants the risk is forprosthetic subsidence and/or periprosthetic fracture.

A technical consideration, shared by all surgical approaches, involvesthe sizing and placement of both prosthetic components. In regard to thefemoral component, correct size directly affects the depth the componentcan be seated into the bone. Placed too deep and the leg ends up beingleft short, but more commonly, placing the component proud, leads tolengthening of the leg. Another drawback of posterior based approachesis the need to place the component proud to obtain adequate hipstability.

While success has been obtained with many different femoral componentdesigns, the most successful and popular implant designs involve the useof rigid tapered reamer preparation. Reamer design initially involvedreamers with parallel surface, but now are more popularly designed witha slight taper (3 degree) that is an identical match to the taper designin the femoral implant. This creates an ice cream cone shape to thereamed femur to which an ice cream shape implant is inserted.

To summarize, the potential problems with straight (full length) reamingsystems include the following:

-   -   1. Difficulty in correctly sizing the canal for receipt of the        femoral component. Progressively larger reamers are inserted in        the canal as part of the sizing process. Resistance to reaming        is a major determinant of when to stop increasing the diameter        of the reamer (and subsequently the femoral component size).        When using full length reamers, often it isn't possible to        determine if the resistance is occurring at the tip, middle or        top of the reamer.    -   2. When the reamers are tapered, the surgeon needs to        simultaneously determine not only when the reamer engages        cortical bone (correctly sized), but also to what depth the        reamer is inserted.    -   3. Incorrectly reaming too deep requires correction by        increasing the size of the femoral component, sometimes to a        size larger than desirable.    -   4. Incorrectly reaming too shallow, if uncorrected, can        over-lengthen an extremity.

While the majority of cases are correctly reamed, based onpreoperatively templating and surgical experience, the outliersresulting in repeating surgical steps, resulting in either error,prolonged surgical time and/or increased surgical trauma. It is for thisreason, surgeons transitioning to muscle sparing approaches anterior tothe trochanter, have circumvented the disadvantages of full lengthreamers, by using shorter rasp based systems. As these implants evolveto shorter length, new challenges and complications are potentiallyintroduced. Rasp based systems have unique sizing challenges and havebeen associated with higher periprosthetic fracture rates, both intraand postoperatively. Additionally, shorter stems have potentially lessstability and surface area for bone attachment and ingrowth, andsubsequently painful implants requiring revision.

Therefore, there is a need for a hip replacement procedure that allowssurgeons using long stem, reamer based systems to continue transition tomuscle sparing approaches, based anterior to the trochanter, withouthaving to experiment with new shorter stem designs. The technique shouldinclude methods and devices for sizing the femur, depth of placement andreceipt of the femoral component without increased damage to nearbytissue and abductor muscle.

SUMMARY

This patent application is based upon the following beliefs:

-   -   1. Tapered reamer systems have advantages over short stemmed        rasp based systems.    -   2. Muscle sparing approaches, anterior to trochanter have the        advantages of lower dislocation rates, without disadvantages        related to abductor muscle trauma.    -   3. The disadvantages of reamer based systems can be circumvented        by not using long reamers with cutting teeth along the full        length and instead breaking the reaming into three parts;        distal, proximal and finally middle region.    -   4. It is the distal reaming that best determines prosthetic        implant size.    -   5. It is the proximal reaming, combined with rasping, that is        responsible for the majority of ingrowth for the proximally        coated portion of tapered implant designs.    -   6. While traditionally, acetabular preparation and placement is        performed prior to the femoral side, preparation limited to        proximal and distal would be helpful in facilitating femoral        retraction and preliminary gap measurements (between femoral cut        and acetabular component).    -   7. It is the middle region reaming that determines and maintains        the depth/height at which the final component resides.    -   8. Middle region reaming is the most destructive portion of        reaming techniques and can be limited in:        -   a. reamer cutting teeth length and        -   b. number of reamer passes.    -   9. The number of middle reamer passes can be limited by        -   a. accurately determining final implant size and depth,        -   b. performing proximal and distal preparation separately and            prior to middle region,        -   c. performing middle region reaming after distal and            proximal reaming.

The patent application is directed to devices and methods for hipreplacement surgery. One aspect is directed to devices and methods forpreparing the femoral canal for implanting a femoral component. This mayinclude initially reaming a proximal region of the femoral canal and adistal region of the femoral canal. These regions are reamed withoutreaming a middle region of the femoral canal. The distal and proximalregions may be reamed in various orders (i.e., distal first or proximalfirst). In one embodiment, the femur is otherwise fully prepared in sizeand depth prior to the middle region reaming. At some time thereafter,the middle region is reamed. The middle region reamer level may be thefinal determinate of femoral component placement.

Another aspect is directed to the use of a dummy implant in the femoralcanal. The dummy implant may include a portion that extends into thefemoral canal and a section that extends outward. The dummy implant maybe used for one or more of retraction of the femur, use with a measuringdevice to determine a gap with the acetabulum, and as a cutting blockfor making a revised femoral cut.

One embodiment disclosed is directed to a method of performing a hipreplacement surgical procedure. The method includes: reaming distal andproximal regions of the femoral canal without reaming a middle region ofthe femoral canal with the middle region extending between the distaland proximal regions; inserting a dummy implant into the femoral canal;using the dummy implant for performing at least one of retracting thefemur and determining a gap between an acetabulum and the dummy implant;after using the dummy implant, removing the dummy implant from thefemoral canal and reaming the middle section of the femoral canal; andinserting a femoral component into the reamed femoral canal.

The method may include reaming the distal and proximal regions of thefemoral canal with a single reaming tool having first and second cuttingsections.

The method may include inserting the dummy implant into the femoralcanal by positioning a plate at a proximal end of the dummy implant overa proximal end of the femur.

The method may further include inserting a mid-shaft reamer a singletime into the femoral canal while reaming the middle region of thefemoral canal.

The method may include that determining the gap between the acetabulumand the dummy implant includes attaching a tensometer to the dummyimplant and gauging a distance to the acetabulum. The method may alsoinclude inserting a pivot pin of the tensometer into an opening in aplate of the dummy implant that extends outward beyond the femoralcanal.

The method may also include positioning a soft tissue reamer protectorat an end of the femur and inserting a mid-shaft reamer into theprotector and reaming the middle region of the femoral canal. This mayinclude contacting a stop flange on the mid-level reamer against theprotector and limiting a depth of the reaming of the middle region ofthe femoral canal.

The method may include using a plate on the dummy implant that extendsoutward over the proximal end of the femur as a cutting guide andremoving a portion of the proximal end of the femur.

The method may include using the dummy implant and retracting the femurand subsequently implanting an acetabular component.

The method may also include accessing the femur using an anteriortrochanteric-based approach.

Another embodiment is directed to a method of performing a hipreplacement surgical procedure. The method includes: preparing a distalregion of the femoral canal without preparing a middle region of thefemoral canal; preparing a proximal region of the femoral canal withoutpreparing the middle region of the femoral canal; inserting a dummyimplant with a first section extending within the proximal region, themiddle region, and the distal region of the femoral canal, and a plateattached to the first section extending outward over a proximal end ofthe femur; attaching a tensometer to the plate and determining a gapbetween the femur and the acetabulum; cutting the proximal end of thefemur along the plate; removing the dummy implant and preparing themiddle region of the femoral canal without further preparing the distalregion and the proximal region; and implanting a femoral component intothe femur.

The method may further include contacting the dummy implant andretracting the femur away from the acetabulum and attaching anacetabular component to the acetabulum.

The method may include preparing the middle region of the femoral canalwithout further preparing the distal region comprises passing amid-shaft reamer a single time along the middle region.

The method may include that the femoral component includes a unibodyconstruction and accessing the femur with an anterior trochanteric-basedapproach.

The method may include preparing the distal region and the proximalregion with a single tool that includes first and second cuttingsections that are separated by a non-cutting section. The method mayalso include rotating the tool in a first direction and preparing thedistal region with the first cutting section, and rotating the tool inan opposing second direction and preparing the proximal region with thesecond cutting section. The method may also include sliding the secondsection of the tool that includes the second cutting section over afirst section that includes a first cutting section.

Another embodiment is directed to a method of performing a hipreplacement surgical procedure. The method includes: reaming a distalregion of the femoral canal with a distal reamer without reaming amiddle region or a proximal region of the femoral canal; reaming theproximal region of the femoral canal with a proximal reamer withoutreaming the middle region or the distal region of the femoral canal;inserting a dummy implant into the femoral canal, the dummy implantincluding a first section that extends into the proximal region, themiddle region, and the distal region of the femoral canal; positioning aplate on the dummy implant over a proximal end of the femur; applying aforce to the dummy implant and retracting the femur; attaching ameasuring tool to the plate of the dummy implant and measuring a gapbetween the femur and the acetabulum; cutting the proximal end of thefemur along the plate; removing the dummy implant from the femur; afterremoving the dummy implant, reaming the middle region of the femoralcanal without reaming the distal region or the proximal region; andimplanting a femoral component and contacting the femoral componentagainst the distal, proximal, and middle regions of the femoral canal.

The method may also include reaming the distal and proximal regions witha single tool that includes a distal cutting section and a proximalcutting section and an intermediation non-cutting section that alignswith the middle region when the tool is fully inserted into the femoralcanal.

The method may include that the femoral component includes a unibodyconstruction and accessing the femur with an anterior trochanteric-basedapproach.

These various aspects may be used together in a single procedure.Alternatively, the various aspects may be used separately to includejust the use of the subsequent middle region reaming, and just the useof the dummy implant.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side schematic view of a hip replacement implant mountedwithin a patient.

FIG. 2 is a perspective view of a femoral component with schematicallyindicated distal, proximal, and intermediate sections.

FIG. 3 is a perspective view of a dummy implant.

FIG. 4 is an exploded perspective view of a hip replacement implantincluding a femoral component and an acetabular component.

FIG. 5 is a side schematic view of the relative sizes, shapes, andpositioning of a dummy implant and a femoral component relative to afemur.

FIG. 6 is a side view of a distal reamer positioned in the femoral canalwith the femur illustrated in cross section.

FIG. 7 is a side of a proximal reamer positioned over a distal reamer inthe femoral canal with the femur illustrated in cross section.

FIG. 8 is a cross-sectional side view of a femoral canal with reameddistal and proximal regions.

FIG. 9 is a side view of a dummy implant positioned in a femoral canalwith the femur illustrated in cross section.

FIG. 10 is a side view of an impactor positioned relative to a dummyimplant with the femur illustrated in cross section.

FIG. 11 is a side view of a dummy implant used as a cutting guide withthe femur illustrated in cross section.

FIG. 12 is a top view of a dummy implant positioned in a femoral canal.

FIG. 13 is a perspective view of a retractor engaged with a dummyimplant.

FIG. 14 is a perspective view of a tensometer.

FIG. 15 is a side view of a tensometer positioned to measure a gapbetween a femur and acetabulum.

FIG. 16 is a perspective view of a tensometer with the head includingtwo visually distinct sections.

FIG. 17 is a side view of a mid-shaft reamer positioned in the femoralcanal with the femur illustrated in cross section.

FIG. 18 is a side view of a protector positioned at a proximal end ofthe femur and with a mid-shaft a reamer positioned in the femoral canalwith the femur illustrated in cross section.

FIG. 19 is a side view of a rasp.

FIG. 20 is a side view of a distal reamer.

FIG. 21 is a side view of a portion of a proximal reamer.

FIG. 22 is a schematic sectional side view of a distal reamer attachedto a proximal reamer.

FIG. 23 is a side view of a combined reamer with proximal and distalcutting sections positioned in a femoral canal with the femurillustrated in cross section.

FIG. 24 is a side view of a dummy implant.

DETAILED DESCRIPTION

The present application is directed to methods and devices forperforming hip replacement procedures. While this application could bedirected to any hip replacement surgical procedure, it is mostapplicable for overcoming the difficulty of placing a long stem femoralcomponent through anterior trochanteric-based approaches (i.e.,Anterolateral, mini-Watson-Jones, Rottinger, Smith-Peterson, Mattamodification).

The methods and devices include a reaming technique with initialproximal and distal reaming, followed by middle region reaming using areamer with reduced cutting teeth length. The middle region reaminglevel is the final determinate of placement of a femoral component, andthe femur is otherwise prepared in size and depth to receive thecomponent before reaming with the middle region reamer. The middleregion reamer includes reduced cutting teeth length and is passeddefinitively once to reduce and/or eliminate damage to nearby tissue.The technique further includes placement of a dummy implant within thefemur. The dummy implant provides multiple functions, including but notlimited to forming a cutting footprint for preparation of the femur,providing a cutting block for a revised femoral cut, providing a guidefor sizing, providing a base for retraction of the femur, engagementwith a tensometer, and for assisting with a lowering neck cut.

FIG. 1 illustrates a hip replacement implant 10 positioned within apatient. The implant 10 includes a femoral component 11 that is attachedto the femur 100, and an acetabular component 80 that is attached to theacetabulum 101 in the pelvic bone 107. The femoral component 11 includesa head 15 that seats within a receptacle of the acetabular component 80.This replacement joint replicates the hip joint and provides forpivoting movement of the femur 100 relative to the pelvic bone 107.

Techniques disclosed in the present application include sizing of thefemoral medullary canal 103 to receive the femoral component 11. Thismay include initial sizing of the femoral medullary canal 103(hereinafter referred to as the femoral canal or canal 103) initially atdistal and proximal locations. Sizing of a middle region of the canal103 is subsequently performed and is the final determinate of theplacement of the femoral component 11.

This concept is illustrated in FIG. 2 that includes the femoralcomponent 11 with an elongated shape including a neck 12 and a distaltip 13. The distal region of the canal 103 is reamed to accommodate adistal section 17 of the component 11. Likewise, a proximal region ofthe canal 103 is reamed to accommodate a proximal section 18 of thecomponent 11. After both the distal and proximal regions of the canal103 have been prepared, a middle region is then reamed to accommodate amiddle section 19 of the component 11.

The extent of reaming of the distal and proximal regions of the canal103 is determined using a dummy implant 20 that is inserted into thecanal 103. The dummy implant 20 closely matches the cross-section of thedistal section 17 and proximal section 18 of the femoral component 11.As illustrated in FIG. 3, the dummy implant 20 is sized to fit withinthe canal 103 after reaming of the distal and proximal regions. Thedummy implant 20 includes a distal body 26 that corresponds to the sizeof the distal section 17 of the femoral component 11 and is sized to fitwithin the reamed distal region of the femoral canal. The dummy implant20 also includes a shaft 25 with an enlarged section 27 that correspondsto the proximal section 18 of the femoral component 11 and is sized tofit within the reamed proximal region of the femoral canal 103. Becauseof the tapered shape of the femoral component 11, the enlarged section27 includes a greater width than the distal body 26. In one embodiment,the tapered shape provides for a 3° taper between the enlarged section27 and the distal body 26. A foot-plate 23 is positioned at the proximalend 22 and is sized and oriented to extend over the proximal end of thefemur 100. The foot-plate 23 is positioned at an angle α relative to theenlarged section 27 to approximate the neck cut of the femur 100. Anelongated shaft 25 extends between the enlarged section 27 and thedistal body 26.

FIG. 4 illustrates one embodiment of an implant 10 that includes thefemoral component 11 and the acetabular component 80. The femoralcomponent 11 includes an elongated shape with a distal end 13 and thedistal, proximal, and mid sections 17, 18, 19. The distal section 17includes a generally circular cross-sectional shape, with the proximalsection 18 having a substantially oval cross-sectional shape thatincreases in size in a proximal direction. The neck 12 extends laterallyoutward and includes a mount 14 to receive a head 15. The head 15includes a receptacle that fits onto the mount 14 and a sphericalexterior shape that engages with the acetabular component 80.

The acetabular component 80 is configured to attach to the acetabulum101 and receive the head 15 of the femoral component 11. The acetabularcomponent 80 includes a shell 81 and a liner 82 that each includes aconcave shape. The shell 81 is initially attached to the acetabulum 101with the liner 82 fitting within the shell 81. The liner 82 includes areceptacle sized to engage with the head 15 to form the joint.

Examples of implants 10 include but are not limited to a Synergy hipsystem with a Synergy Porous Plus HA femoral component available fromSmith & Nephew of Memphis, Tenn., a Summit hip system available fromDepuy J&J of Warsaw, Ind., and an Epoc Hip System available from Biometof Warsaw, Ind.

FIG. 5 illustrates relative sizes, shapes, and placements of the dummyimplant 20 and the femoral component 11 relative to the proximal femur100. As illustrated, both the dummy implant 20 and femoral component 11have shapes and sizes that correspond to the proximal femur 100. Thefemur 100 is initially prepared to receive the dummy implant 20. Thedummy implant 20 is sized to fit within the femoral canal 103 and isconfigured to be used for a variety of different processes that aredescribed in detail below. Once complete, the dummy implant 20 isremoved and the femoral component 11 is implanted for forming a finalcomponent of the hip replacement implant.

Hip replacement procedures access the femur 100 and acetabulum 101through various surgical approaches, including: approaches posterior tothe trochanter such as the Southern, Moore, Gibson, Kocher-Langenbeck,maximum splitting, and posterolateral approaches. Other approachesinclude those anterior to the trochanter such as Smith-Peterson,Rottinger, Heuter, direct anterior, Watson Jones, lateral,anterolateral, abductor split, trans-gluteal, Bauer, trans-lateral, andHardinge. Additional approaches may include trans-trochiantericapproaches. The methods and devices of the present application areapplicable to procedures using any of these approaches, or anyapproaches that may be favored by particular surgeons.

The described procedure uses an anterior approach. In general, ananterior approach is a more muscle sparing approach than a posteriorapproach. Hip replacement procedures using an anterior approach mayresult in a shorter recovery time for the patient because of the lessinvasive aspects of muscle-cutting requirements to access the surgicalsite. Further, anterior approaches may allow for the use of implants 10that have historically resulted in a lower dislocation rate. In oneembodiment, the methods and devices are used with the Rottingerprocedure. The Rottinger procedure may be favored by surgeons forvarious reasons, including but not limited to: the procedure may beperformed using a less-expensive operating table that places the patientin a lateral position; the ability to perform range of motion andstability testing after insertion of the implant 10; the ability toperform the procedure without the need for X-ray visioning; thereduction or elimination of issues with the femoral cutaneous nerve; andthe wide applicability for use of the procedure with a variety ofdifferent femoral components 11.

Prior to the surgical procedure, preoperative planning may occur fordetermining an estimation of the range of component sizes. The planningincludes the placement of templates of the prosthetic silhouette overradiographs of the hip. The templates have multiple sizes matching themultiple sizes of the available implants. The templates provide areasonably accurate prediction of the final components size andplacement. The templating is usually performed well in advance of thesurgical procedure.

Once the preoperative planning is complete, the surgical phase of theprocedure can commence. The patient is placed in a lateral position andsecured on the bed in a stable position. A modified peg board is securedto the table to convert the table into a split configuration for theoperative leg to be extended, abducted, and externally rotated forfemoral preparation. The entire leg may be prepped and draped into theoperative field for full range of motion and demonstration of hipstability once the trials and implants are implanted.

The actual placement of the surgical incision will depend on whichsurgical approach is being used. The general principles shared by allapproaches include: an incision is made through the skin andsubcutaneous tissue and fat, down to the fascia, which is usuallyincised in line with the skin incision. Once this first fascial layer isopened, the surgeon navigates past the muscles surrounding the hip, toexpose the capsule of the hip joint. The capsule can be either openedfor later closure or excised, but is usually preserved for later closureat the end of the procedure. Once the hip is exposed, either the femoralneck is osteotomoized, or the hip is dislocated and then the neck isosteotomized. If the osteotomy occurs first, then the femoral head willneed to be removed at some point later in the procedure. Either way,once the femoral neck has been cut, the proximal femur is then exposedand mobilized.

The surgical site is established that provides access to the proximalsection of the femur 100 and the acetabulum 101. While the hip can bedislocated with extension and external rotation, it is often safer toosteotomize the neck and remove the femoral head when the acetabulum 101is fully exposed. Once the femur 100 is mobilized, a final cut is madeon the femoral neck. Sometimes this osteotomy is performed in one cut,but often includes two cuts with the second cut attempting to make thelevel of the neck cut at approximately the final level. After the finalfemoral neck cut is made, the obturator externus tendon is detached fromthe femur 100. This allows for improved femoral exposure. With the neckand head of the femur 100 removed, the leg is brought back into aneutral position and the acetabulum 101 is exposed with placement ofposterior and anterior acetabular retractors. The femoral head can beremoved at this time.

The femur 100 is exposed with extension, adduction, and externalrotation. In one embodiment, a two-pronged retractor is placed under thecalcar medially to expose the cut surface of the proximal femoral neck.A box osteotome is used to open the femoral canal medial to the greatertrochanter and centered in the femoral neck. Additional preparation,such as removing additional bone from the greater trochanter, may benecessary to form an adequate opening for receiving and positioning thefemoral component 11.

The femoral canal 103 is prepared by reaming the distal region 110 usinga series of graduated distal reamers 30. FIG. 6 illustrates one of thedistal reamers 30 for sizing the distal region 110 of the canal 103. Theentire femoral canal is reamed with progressively increasing diametersuntil distinct resistance and chatter are obtained. The diameter ofreamer, when this occurs will determine the femoral component size. Thismethod of reaming not only determines implant size, but also reduces thechance of a pedestal being created by full length cutting reamers.Resistance seen with subsequent reamers, will unlikely be secondary todistal positioning or narrowing of the distal canal.

The distal reamer 30 includes an elongated shaft 31 with a ball headcutting section 32. The shaft 31 includes a relatively narrow width andis flexible to allow for the cutting section 32 to remain centeredwithin the femoral canal 103. The shaft 31 may include a substantiallysmooth exterior surface and/or a circular cross-sectional shape toprevent damaging the tissue in proximity to the surgical site duringrotation of the reamer 30. One or more markings 34 may be positionedalong the shaft 31 that are visually aligned with the greater trochanterto determine a depth of the reaming. The cutting section 32 may includevarious configurations for sizing the femoral canal 103. The cuttingsection 32 may include a set of parallel straight or helical cuttingedges. The edges may be orientated at an angle and include an underneathundercut. Helical edges may be aligned in either clockwise orcounter-clockwise spirals.

Reaming of the distal region 110 is performed using a series ofgraduated reamers 30 with increasing diameter cutting sections 32. Thereamers 30 are inserted into the femoral canal 103 in order with eachsubsequent reamer 30 being larger than the previous reamer. The initialreamer 30 may start at a diameter approximating 8 mm with subsequentreamers 30 increasing in size up to a diameter of 22 mm. The process mayinclude insertion of graduated reamers 30 and reaming of the canal 103to the point of chatter. At this point, the next reamer 30 in the seriesis passed along the distal section 110 for final reaming. The use of theone additional reamer 30 of greater diameter causes reaming around theentirety of the distal region 110 (i.e., 360 degree bone contact). Thisprovides for engagement about the entire circumference of the distalsection 17 when the femoral component 11 is finally implanted into thefemur 100.

The size in diameter of the final distal reamer 30 determines the actualsize of the implant 10. Implants 10 are often numbered from smallest tolargest with either an arbitrary numbering system (e.g., 1-12) or anumber system based on a diameter of the implant at a location/level onthe actual implant such as the distal section. In one embodiment, afirst implant has a distal diameter of 10 mm and a proximal diameter of14 mm, with a second larger implant having an 11 mm distal diameter anda 15 mm proximal diameter. The location that defines the distal diameterfor a given implant is somewhat arbitrary, but represents the intendedlevel at which the component fully fills the canal 103. For the taperedstem design, this would be at the lower end of the distal section 17 asillustrated in FIG. 2.

The depth of insertion of the reamer 30 into the canal 103 may bedetermined by a visual mark 34 located along the shaft 31 that isaligned with the greater trochanter as determined during pre-operativeplanning. A surgeon may further rely on the tactile feel caused bycontact of the reamer 30 within the interior wall of the canal 103 todetermine the insertion depth. The surgeon should error on reamingfurther than the length of the eventual implant. There really isn't adepth limit to creating a symmetric canal at the final distal diameter.A continuous hollow cylinder does not leave a stress riser in bone or apedestal to prevent implant subsidence. The depth markings 34 along theshaft 31 may be provided to ensure that the surgeon reams far enough toaccommodate the implant.

After the distal reaming, a proximal reamer 40 is inserted to ream theproximal region 111 of the femoral canal 103. The proximal reamingshapes and sizes the canal 103 to accommodate the proximal section 18 ofthe femoral component 11. As illustrated in FIG. 7, the proximal reamer40 may be configured to be used in conjunction with the distal reamer 30by extending over the shaft 31 of the distal reamer 30 (the shaft 31 ofthe distal reamer that extends through the proximal reamer 40 isillustrated in dashed lines in FIG. 7). The proximal reamer 40 includesan elongated shape with a shaft 41 and a cutting section 42. A centralopening extends longitudinally through both the shaft 41 and cuttingsection 42 to allow the proximal reamer 40 to be inserted over and movedalong the shaft 31 of the distal reamer 30. The shaft 41 includes acircular cross-sectional shape with a smooth exterior surface to preventdamage to the nearby tissue during rotation of the reamer 40. Thecutting section 42 may include the same or different cuttingconfiguration as the cutting section 32 of the distal reamer 30. Thecutting section 42 may include a set of parallel straight or helicalcutting edges. The edges may be orientated at an angle and include anunderneath undercut. Helical edges may be aligned in either clockwise orcounter-clockwise spirals. In one embodiment, the cutting section 42 isoriented in an opposite direction from the cutting section 32 of thedistal reamer 30. The proximal reamer 40 is rotated in an oppositedirection than that of the distal reamer 30. This opposite orientationensures that should the movement of the proximal reamer engage and movethe distal reamer, that there is no reaming in the distal region 110during the proximal reaming process.

The depth of insertion of the proximal reamer 40 into the canal 103 maybe determined by a visual mark located along the shaft 41 that isaligned with the greater trochanter. Another manner of determining theinsertion depth is the tactile feel caused by contact of the cuttingsection 42 with the interior wall of the canal 103. The depth of theproximal reaming is ideally enough to accommodate any revisions of theneck cut that may occur in subsequent steps of the surgical procedure.

During proximal reaming, the proximal reamer 40 is inserted over theshaft 31 of the distal reamer 30 and moved downward into the canal 103.The proximal reaming occurs during a single pass of a single proximalreamer 40 (i.e., there are no graduated reaming systems or multiplepasses of the single proximal reamer 40). During the reaming, pressuremay be applied to the proximal reamer 40 in the direction of the greatertrochanter to lateralize the proximal region 111.

The cutting section 42 is positioned in the canal 103 prior to reamingto reduce and/or eliminate contact of the cutting section 42 with thesurrounding tissue during rotation of the reamer 40. A portion of thecutting section 42 may extend outward from the canal 103 as illustratedin FIG. 7, but the amount that extends outward is limited and is usuallycontained within the retracted surgical site to prevent contact with thetissue. The first section 41 of the shaft that extends outward from thecutting section 42 is structured to prevent damage to the tissue in theevent of contact. This structure may include a substantially smoothsurface, and may also include a circular cross-sectional shape.

Each of the reamers 30, 40 are designed to prevent damage to thesurrounding tissue. The proximal sections of the reamers 30, 40,particularly the shaft 31 of the distal reamer 30 and the shaft 41 ofthe proximal reamer 40, include surfaces designed to reduce and/oreliminate damage to the surrounding tissue in the event of contact. Inone embodiment, the shafts 31, 41 are smooth and do not catch orotherwise cut or damage the tissue if there is inadvertent contactduring the reaming of the canal 103. The cutting sections 32, 42 arepositioned along the reamers 30, 40 to remain partially or completelypositioned in the canal 103 during the reaming procedures.

One or both of the reamers 30, 40 may be operated by hand.Alternatively, one or both reamers 30, 40 may include a mount forattachment to a power tool for driving the reamers.

At this stage of the surgical procedure, the femoral canal 103 has beenreamed along the distal and proximal regions 110, 111 as illustrated inFIG. 8. This sizing of the femoral canal 103 creates a silhouette thatmatches the shape and size of the dummy implant 20. FIG. 9 illustratesthe dummy implant 20 inset within the femur 100. The dummy implant 20seats in the femoral canal 103 with the distal body 26 aligned along thedistal region 110 and the enlarged section 27 aligned along the proximalregion 111. The distal body 26 contacts against the reamed distal region110 of the femoral canal and the proximal section 27 contacts againstthe reamed proximal region 111 of the femoral canal. The elongated shaftextends between the enlarged section 27 and body 26 along the middleregion 112 that is yet to be reamed. The shaft 27 is spaced away fromthis non-reamed middle region 112. Further, the foot-plate 23 extendsover the top of the proximal femur and femoral neck. The dummy implant20 substantially matches the dimensions of the femoral component 11except for the section that aligns with the middle region 112 of thefemoral canal 103.

The dummy implant 20 provides for numerous functions during the surgicalprocedure. The dummy implant may be used to perform one or more of thefollowing functions: (1) shaping/cutting the proximal neck of the femur100 to accommodate the femoral component 11; (2) providing a templatefor cutting a surface of the proximal neck of the femur 100; (3) sizingthe femoral canal 103 relative to the femoral component 11; (4)retracting the femur; (5) engaging a tensometer to determine a necklength of the femoral component 11; and (6) potentially lowering theneck cut.

The first function includes cutting/crushing/compressing the cancellousbone within the proximal femoral neck during insertion of the dummyimplant 20. The foot-plate 23 of the dummy implant 20 corresponds to thecross section of the final implant at that level. As illustrated in FIG.9, the foot-plate 23 includes a cutting edge 28 along a lower surface.The cutting edge 28 may be isolated to just the tip of the foot-plate23, or may extend along a larger section of the foot-plate 23. Duringinsertion of the dummy implant 20 into the femoral canal 103 in thedirection of arrow A, the cutting edge 28 contacts against a medialportion and cuts and shapes the femoral neck. The force necessary to cutthe femoral neck may be applied by hand, or may require the use of amallet that strikes against the upper surface of the foot-plate 23.

An impactor 120 may be used to apply a force to the dummy implant 20. Asillustrated in FIG. 10, the impactor 120 includes a lower edge 121 thatsubstantially matches the foot-plate 23 of the dummy implant 20. Forceexerted on the impactor 120 is transferred to the dummy implant 20, andmay be used to impact the dummy implant 20 by exact increments. Theimpactor 120 may be used if the surgeon wants to lower the neck cut onthe femur 100.

The second function of the dummy implant 20 is to provide a cuttingtemplate for the final femoral neck cut. Prior to this point, a roughestimate of the neck cut has been made during the surgical procedure.The dummy implant 20 seats within the femoral canal 103 with thefoot-plate 23 positioned within an interior portion of the proximal endof the femur 100. The exposed proximal end of the femur 100 may includean uneven shape with one or more portions 119 extending above the topsurface of the foot-plate 23. As illustrated in FIG. 11, the uppersurface of the foot-plate 23 functions as a cutting guide to remove theone or more portions 119. The upper surface is substantially flat andforms an alignment surface against which the surgeon may position ablade of a cutting instrument. The blade is moved along the length ofthe foot-plate 23 thereby removing the one or more portions 119 thatextend superiorly beyond the foot-plate 23.

The third function includes sizing the femur 100 relative to the dummyimplant 20. The foot-plate 23 of the dummy implant 20 matches thedimensions of the proximal section 18 of the femoral component 11.Further, the dimensions of the distal body 26 match distal section 17 ofthe femoral component 11. This matching provides an indication to thesurgeon about the fit and placement within the femoral canal 103. Thedummy implant 20 also provides the first visual indication of how theimplant will seat within the femur 100. As illustrated in FIG. 12, thefoot-plate 23 replicates the shape of the proximal section 18 of thefemoral component 11 (see FIG. 2) allowing the surgeon to visuallydetermine the position relative to the femoral canal 103 and femur 100.Based on the tactile feel of the dummy implant 20 within the femoralcanal 103 and/or the visual placement of the dummy implant 20 relativeto the femur 100, the surgeon is able to determine if adjustments arenecessary.

The fourth function of the dummy implant 20 is to retract the femur 100away from the acetabulum 101. The dummy implant 20 that extends outwardfrom the femur 100 provides an attachment that can link to a cobraretractor and be used to retract the femur 100. FIG. 13 illustrates aretractor 130 engaged with the dummy implant 20 to retract the femur 100away from the acetabulum 101. The dummy implant 20 protects theintegrity of the proximal femur 100 and the femoral neck while the cobraretractor 130 forcibly pushes the femur 100 aside for acetabularpreparation. Previous retraction methods have included applying a forcedirectly to the femur 100 at a location at or in proximity to theproximal femur 100.

Once the femur 100 is being retracted through the dummy implant 20 asillustrated in FIG. 13, the acetabulum 101 is then reamed to form anarea for receiving the acetabular component shell 80. Once theacetabulum 101 is prepared, the acetabular component 80 is placed withinthe patient and attached to the acetabulum 101 using various methods,including one or more bone screws. Bone screws may be used to attach theshell 81 to the acetabulum 101, with the liner 82 being subsequentlyplaced over the bone screws and attached to the shell 81. The liner 82is positioned to later receive the head 15 of the femoral component 11.

The fifth function of the dummy implant 20 is for use with a tensometer50 to determine a distance between the femoral neck cut and theacetabular hip center. This gap between the acetabular component 80 andthe implant 20 determines the neck size for the femoral component 11.Preferably, components 11, 80 can be positioned to minimize of eliminatethe neck. FIG. 14 illustrates a tensometer 50 to measure the gap. Thetensometer 50 includes a pin 54 at the first end of the handle 52 sizedto fit in the opening 24 in the foot-plate 23 of the dummy implant 20.The end of the pin 54 may include a spherical shape to engage with theopening 24. Once the pin 54 is attached to the dummy implant 20, aspherical head 56 at the first end of the handle 51 is seated into theacetabulum component 80. The distance between the components is measuredto determine the necessary neck length on the femoral component 11.Ideally, tactile and/or audible feedback occurs when the spherical head56 seats into the acetabulum component 80 to indicate solid engagement.

FIG. 15 illustrates an embodiment of the tensometer 50 positioned todetermine a distance between the acetabular hip center and the femoralneck cut. The spherical head 56 is seated in the acetabulum component 80on the acetabulum 101, and the pin 54 is mounted to the dummy implant20.

While the femoral component 11 is defined by the proximal anatomy of thefemur 100, the acetabulum component 80 can be orientated/rotated freelyin all directions. If the component 80 is not oriented properly to thefemur 100, hip instability could occur. The combined version (sum of thecup and stem anteversion) has been reported to be in the 25-45 degreerange. To address this issue, the tensometer 50 will have a dualpurpose. In addition to assessing space/tension between the femur andacetabulum (head/neck length), it will also be able to assess cupversion in relationship to the acetabulum. The head 56 of the tensometer50 will have incorporated the ideal version/relationship sought by thesurgeon, by dividing the femoral head 56 into two sections 56 a, 56 b asillustrated in FIG. 16. The two sections 56 a, 56 b are visuallydifferentiated, such as through the use of two different colors. Whenthe circumference of the acetabulum component 80 overlaps the linebetween the two sections 56 a, 56 b, proper cup version has beenobtained. If portions of the two sections 56 a, 56 b can besimultaneously seen by the surgeon, when the ball is reduced and withthe leg in a neutral position, then the version is outside parametersand the surgeon should re-orientate the acetabular component 80, priorto proceeding on to the femoral component 11.

The sixth function of the dummy implant 20 is to provide a gauge fordetermining how to further treat the femur 100. If the engagementbetween the spherical head 56 and the acetabulum component 80 iscorrect, then no further treating of the femur 100 is necessary and thedummy implant 20 can be removed from the femur 100. If the measured gapis too long indicated by the engagement of the spherical head 56 andacetabulum component 80 being too tight, the dummy implant 20 can beimpacted a set distance further into the femur 100 and re-cut (see FIG.10). The additional cut lowers the position of the dummy implant 20relative to the femur 100. Once the revision cut is complete, anothergap measurement may be taken to determine whether the gap is nowadequate. If the measured gap is too short with an engagement that istoo loose, the depth of reaming of the middle region 112 of the femoralcanal 103 will be adjusted to accommodate for the shortness as will bedescribed below.

Once the various procedures with the dummy implant 20 are complete, theimplant 20 is removed from the femur 100. Once removed, reaming of themiddle region 112 of the femoral canal 103 is performed using amid-shaft reamer 70. This final mid-shaft reamer 70 matches the diameterof the implant size determined during the distal reaming. As illustratedin FIG. 17, a mid-shaft reamer 70 is inserted into the canal 103 forreaming the middle region 112 positioned between the distal and proximalregions 110, 111 and that has not previously been prepared by the distalor proximal reamers 30, 40. The mid-shaft reamer 70 includes anelongated shape with a distal section 71 that aligns with thepreviously-reamed distal region 110, and a proximal section 72 thataligns with the previously-reamed proximal region 111. Each of thesepreviously-reamed sections 71, 72 match the shape of the femoralcomponent 11 and function to center the mid-shaft reamer 70 along thefemoral canal 103. The sections 71, 72 each include a smooth exteriorsurface such that there is no additional reaming of the distal andproximal regions 110, 111. A cutting section 73 is positioned along anintermediate length of the reamer 70 between sections 71, 72. Thecutting section 73 includes a tapered shape with cutting surfacessimilar to the cutting sections 32, 43 of the reamers 30, 40 asdescribed above. The diameter of the cutting section 73 is paired butnot identical to the last diameter of the distal reamer 30. The diameterof the cutting section 73 also matches the proximal diameter of thefemoral implant 11. A shaft 75 extends outward in a proximal directionfrom the second section 72. The shaft 75 may include a smooth exteriorsurface and a circular cross-sectional shape to prevent damage in theevent of contact with the tissue.

The depth of reaming of the middle region 112 may be controlled invarious manners. A flange 74 is positioned along the shaft 75 andincludes a greater width than the shaft 75. The flange 74 functions as adepth stop and contacts against or otherwise be aligned with the femur100 to control an extent of reaming of the femoral canal 103. The flange74 may be adjustable along the length of the shaft 75 to accommodatevariations in the desired reaming levels. The level of the flange 74 isdetermined in part by the measurements taken from the tensometer 50. Theflange 74 is adjustable in height/position and may be adjusted along theshaft to accommodate the implant when the gap measured between the dummyimplant 20 and the acetabular component 80 is too loose. The insertiondepth of the mid-shaft reamer 70 may also be controlled by the size ofthe distal section 71. The size of the distal section 71 causesengagement with the reamed distal region 110 and prevents furtherinsertion into the femoral canal 103.

Preferably, the previous preparation (proximally, distally, andfootplate) allows the surgeon to perform a single pass with onemid-shaft reamer 70 to size the middle region 112 (as opposed tomultiple passes using a graduated, multiple reamer system such as thatdisclosed for reaming the distal region 110). This single pass includesmoving the mid-shaft reamer 70 along the middle region 112 in a firstdirection into the canal 103, and then moving the reamer in an opposingsecond direction out of the canal 103. This single pass reduces thepotential for damage to the nearby tissue and over-reaming of the canal103.

As illustrated in FIG. 18, the mid-shaft reamer 70 may be used with asoft-tissue reamer protector 90 to protect the femur 100 and control adepth of reaming of the canal 103. The protector 90 includes a body 91that is shaped to match the diameter of the proximal reamer 40. The body91 includes a channel 93 to allow for passage of the mid-shaft reamer70. A contact surface 92 is positioned on an outer side of the body 91in proximity to the channel 93. An arm 94 may extend outward from thebody 91 to allow for the placement and manipulation of the protector 90by the surgeon. The protector 90 also includes an angled flange 95 withan inferior surface 96 that is at the same angle as the foot-plate 23 ofthe dummy implant 20 and matches the dimensions of the uppermost area ofingrowth on the final implant. The flange 95 sets on top of the femoralneck cut and is not inset into the same area 97 where the dummy implant20 resided (i.e., the flange 95 sets on top of the cut edge with therecessed area 97 left by the dummy implant 20 being empty). In anotherembodiment, the protector 90 includes an adjustable lip underneath theflange 95. The lip is inset into the recessed area where the dummyimplant 20 resided.

In use, the protector 90 is placed at the proximal end of the femur 100with the channel 93 being aligned with the femoral canal 103. Thesurgeon than inserts the reamer 70 through the channel 93 and into thecanal 103 to ream the middle region 112. The body 91 protects theproximal end of the femur 100 from being directly contacted by thereamer 70 or a device driving the reamer 70 either of which couldpotentially damage the femur 100. Further, the first section 71 of thereamer 70 may be equipped with a stop flange 74 that is wider than thechannel 93 and contacts against the surface 92 to prevent furtherinsertion and hence the reaming depth along the canal 103. The stopflange 74 may be adjustable along the longitudinal length of the reamer70 to set the reaming depth. Further, indicia may be displayed along thelength to indicate the placement of the stop flange 74 and the resultingreaming depth. Once reaming is complete, the reamer 70 and the protector90 are removed from the patient.

Additional sizing of the canal 103 may occur prior to insertion of thefemoral component 11. This may include the insertion of one or morerasps 140 to further enlarge the size of the canal 103 as appropriate toreceive the femoral component 11. The size of the rasp matches thedimensions from the implant size determined during the distal reaming.FIG. 19 illustrates a rasp 140 that includes a handle 141 with a cuttingsection 142 with teeth 143 positioned along the outer surfaces.

The rasp has three potential functions: 1) to connect together theprevious areas of preparation; 2) to remove cancellous bone inside thecanal within the flair of the femoral canal location medial the areapreviously machined by the reamers; and 3) to be potentially used as atrial component for range of motion (after a neck and head are placed onthe rasp, it can be reduced into the acetabulum and put through a rangeof motion). The concept of the rasp is not new. Most companies producingimplants currently have these rasps available in sizes matching all ofthe available femoral components. The rasp may treat one or moreportions of the femoral canal 103 and form transitions between thedistal, proximal, and middle regions 110, 111, 112. The rasp 140connects the three separate regions that were separately reamed duringthe process.

Once the canal 103 is finalized, the femoral component 11 is insertedinto the canal 103. One or more trial reductions are performed to assessthe engagement of the femoral and acetabular components 11, 12. Thejoint formed by the head 15 placed within the receptacle of theacetabular component 11 is analyzed to determine adequate jointstability, range or motion, and restoration of leg length and offset.Final adjustments to the implant may be made accordingly. Once complete,the procedure is finalized by closing the surgical site.

The procedures described above include the three-section reaming processin combination with the use of a dummy implant 20. These differentprocedures may also be performed independently of one another. By way ofexample, a procedure may include a three-section reaming process withoutthe use of a dummy implant 20. Similarly, a dummy implant 20 may be usedwithout sizing the canal 103 with the three-section reaming process.

The distal, proximal, and middle regions 110, 111, 112 of the canal 103and the corresponding sections 17, 19, 18 of the femoral component 11may have different lengths measured along the axis of the canal 103. Thelengths disclosed in FIG. 2 are one embodiment, with other embodimentsincluding different lengths in one or more of the sections 17, 18, 19.In one embodiment, the length of the middle region 112 is greater thaneither of the distal and proximal regions 110, 111.

FIG. 2 illustrates one embodiment of a hip replacement implant 10.Various other implants 10 may also be used with the methods and devicesdisclosed in the present application.

The reaming on the canal 103 may initially include reaming of the distalregion 110 followed by reaming of the proximal region 111 as illustratedand described above with reference to FIGS. 6 and 7. Alternatively, theproximal region 111 may be initially reamed followed by the distalregion 110.

In a preferred embodiment, the middle region 112 of the canal 103 isreamed definitively once during the procedure. This reduces thepotential for damage to the nearby tissue and over-reaming of the canal103. Other embodiments may include making repeated passes with thereamer 70 through the middle region 112.

The protector 90 may be used with the mid-shaft reamer 70 as illustratedin FIG. 18. The protector 90 may further be used with the distal reamer30 and/or the proximal reamer 40. The reamers 30, 40 may be equippedwith flanges to be used with the protector 90 to control the reamingdepth.

The proximal reamer 40 may include a variety of differentconfigurations. In one embodiment, the proximal reamer 40 is cannulatedand extends over the shaft 31 of the distal reamer 30. In use, theproximal reamer 40 is inserted over the shaft 31 of the distal reamer 30while the distal reamer 30 remains in the femoral canal 103. In thisembodiment, the cutting section 42 of the proximal reamer 40 is orientedin an opposing direction than the cutting section 32 of the distalreamer 30. This opposite orientation provides for just the proximalreamer 40 to be reaming the femoral canal 103, with any rotationimparted to the distal reamer 30 resulting in no material being removedfrom the femoral canal 103. In another embodiment, the distal reamer 30is removed from the femoral canal 103 prior to attaching the proximalreamer 40. The proximal reamer 40 is positioned at the appropriatelocation along the length of the shaft 31 of the distal reamer 30 andlocked into position. The attached distal and proximal reamers 30, 40are then together placed into the femoral canal 103.

The proximal reamer 40 may lock to the distal reamer 30 in a variety ofdifferent manners. FIG. 20 illustrates a distal reamer 30 with anelongated shaft 31 and a distal cutting section 32. Notches 33 extendaround the circumference of the shaft 31 and are spaced apart at setincrements. As illustrated in FIG. 21, the proximal reamer 40 includes acentral channel 43 that extends through the length and is sized to fitaround the shaft 31 of the distal reamer 30. The exterior of theproximal reamer 40 includes a cutting section 42 configured to ream thefemoral canal 103. As illustrated in FIG. 22, the central channel 43 issized for the proximal reamer 40 to slide over the shaft 31 of thedistal reamer 30. The proximal reamer 40 further includes extensions 44that extend outward from sidewalls of the channel 43 and are sized tofit within one of the notches 33 spaced along the shaft 31.

In use, the proximal reamer 40 is inserted onto shaft 31 of the distalreamer 30 and moved along the length to the appropriate longitudinalposition. The shaft 31 may include indicia at each of the notches 33 toindicate a spacing or positioning from the distal cutting section 32.The notches 33 may be positioned at 1 mm increments along an entirety ofportion of the shaft 31. At the desired longitudinal position, theextensions 44 engage with the corresponding notches 33 to fix therelative positions of the reamers 30, 40. The proximal reamer 40 mayfurther include a locking mechanism to prevent further movement.

Another embodiment illustrated in FIG. 23 includes a combined reamer 60with both distal and proximal cutting sections 61, 62. This reamer 60includes a distal cutting section 61 to size the distal region 110 ofthe canal 103, and a proximal cutting section 62 to size the proximalregion 111. An intermediate shaft 63 extends between the sections 61, 62and may be flexible to provide for centering of the reamer 60 within thefemoral canal 103. The threads on the distal and proximal sections 61,62 may be opposite such that rotation of the reamer 60 in a firstdirection sizes a first section of the canal 103, and rotation in anopposing second direction sizes a second section. The specificconfigurations of the cutting sections 61, 62 may be the same as thesections 32, 43 described above for the reamers 30, 40.

The embodiment described above includes proximal reaming occurringduring a single pass of a single proximal reamer 40. Other embodimentsmay include the proximal reamer 40 being passed multiple times along theproximal region 11 of the femoral canal 103. Further, different proximalreamers 40 may be used during the proximal reaming process. Likewise,reaming of the middle region 112 may include multiple passes and/ormultiple mid-shaft reamers 70.

The mid-shaft reamer 70 may include a stand-alone structure asillustrated in FIG. 17. In another embodiment, the mid-shaft reamer 70is configured to be used with the distal reamer 30. The mid-shaft reamer70 includes a longitudinal opening sized to extend over the shaft 31 ofthe distal reamer 30. The mid-shaft reamer 70 is longitudinally movedalong the shaft 31 and includes a cutting section 73 that reams themiddle region 112 in a manner similar to that described above.

The methods and devices for the hip replacement surgery apply to anyreamer-based system. It has been determined that the best results areobtained using a tapered implant, as opposed to a straight stem implant.In specific embodiments, the implant includes a 3° taper.

FIG. 3 illustrates one embodiment of a dummy implant 20. FIG. 24illustrates another dummy implant 20 that includes a proximal portion150 that mimics a rasp, such as that used for additional sizing of thecanal 103 prior to insertion of the femoral component 11 and illustratedin FIG. 19. The dimensions of the proximal portion 150 correspond to theinitial proximal section 144 of the cutting section 142. In oneembodiment, the proximal portion 150 of the dummy implant 20 mimicsabout the first 1-3 cm of the proximal section 144. In a more specificembodiment, the proximal portion 150 mimics about the first 1.5 cm ofthe proximal section 144. In another embodiment, the proximal portion150 includes teeth 143 and mimics the dimensions of the proximal sectionof the femoral component 11

The top surface of the proximal portion 150 forms the plate 23 asdescribed above and may further include one or more openings 24. Asfurther illustrated in FIG. 24, a remainder of the dummy implant 20includes a shaft 25 and distal body 26.

The proximal portion 150 may include various shapes and sizes. In oneembodiment, the proximal portion mimics the shape of the rasp used forsizing of the canal 103. In a specific embodiment, the proximal portion150 has a length of about 1.5 cm that mimics the shape and size of therasp.

Aspects of a total hip arthroplasty are disclosed in the article “TheRottinger approach for total hip arthroplasty: technique and review ofthe literature” by Benjamin J. Hansen, Rhett K. Hallows, and Scott S.Kelley, Curr. Rev Musculoskelet. Med. (2011) 4:132-138. This article isherein incorporated by reference in its entirety.

The various implants and insertion tools may be used during surgicalprocedures on living patients. These may also be used in a non-livingsituation, such as within a cadaver, model, and the like. The non-livingsituation may be for one or more of testing, training, and demonstrationpurposes.

Spatially relative terms such as “under”, “below”, “lower”, “over”,“upper”, and the like, are used for ease of description to explain thepositioning of one element relative to a second element. These terms areintended to encompass different orientations of the device in additionto different orientations than those depicted in the figures. Further,terms such as “first”, “second”, and the like, are also used to describevarious elements, regions, sections, etc and are also not intended to belimiting. Like terms refer to like elements throughout the description.

As used herein, the terms “having”, “containing”, “including”,“comprising” and the like are open ended terms that indicate thepresence of stated elements or features, but do not preclude additionalelements or features. The articles “a”, “an” and “the” are intended toinclude the plural as well as the singular, unless the context clearlyindicates otherwise.

The present invention may be carried out in other specific ways thanthose herein set forth without departing from the scope and essentialcharacteristics of the invention. The present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive, and all changes coming within the meaning and equivalencyrange of the appended claims are intended to be embraced therein.

What is claimed is:
 1. A method of performing a hip replacement surgicalprocedure, said method comprising: reaming distal and proximal regionsof the femoral canal without reaming a middle region of the femoralcanal, the middle region extending between the distal and proximalregions; inserting a dummy implant into the femoral canal, the dummyimplant extending along the distal, middle, and proximal regions of thefemoral canal with an enlarged distal section of the dummy implantcontacting against the reamed distal region of the femoral canal, anenlarged proximal section of the dummy implant contacting against thereamed proximal region of the femoral canal, and a reduced intermediatesection of the dummy implant that extends between the distal andproximal sections positioned along and being spaced away from thenon-reamed middle region of the femoral canal; using the dummy implantfor performing at least one of retracting the femur and determining agap between an acetabulum and the dummy implant; removing the dummyimplant from the femoral canal; and after removing the dummy implant,reaming the middle region of the femoral canal.
 2. The method of claim1, further comprising reaming the distal and proximal regions of thefemoral canal with a single reaming tool having first and second cuttingsections.
 3. The method of claim 1, wherein inserting the dummy implantinto the femoral canal includes positioning a plate at a proximal end ofthe dummy implant over a proximal end of the femur.
 4. The method ofclaim 3, further comprising applying a force to the dummy implant andpenetrating a cutting edge on the plate into the bone and cutting both asurface of the proximal femur and the greater trochanter.
 5. The methodof claim 3, further comprising using the plate as a cutting guide andcutting a surface of the femur along a top edge of the plate.
 6. Themethod of claim 1, wherein determining the gap between the acetabulumand the dummy implant comprises attaching a tensometer to the dummyimplant and gauging a distance to the acetabulum.
 7. The method of claim6, further comprising inserting a pivot pin of the tensometer into anopening in a plate of the dummy implant that extends outward beyond thefemoral canal.
 8. The method of claim 1, further comprising using thedummy implant and retracting the femur and subsequently implanting anacetabular component.
 9. The method of claim 1, further comprisingaccessing the femur using an anterior trochanteric-based approach.
 10. Amethod of performing a hip replacement surgical procedure, said methodcomprising: preparing sidewalls of a distal region of a femoral canalwithout preparing sidewalls of a middle region of the femoral canal;preparing sidewalls of a proximal region of the femoral canal withoutpreparing the sidewalls of the middle region of the femoral canal;inserting a dummy implant into the prepared proximal region, thenon-prepared middle region, and the prepared distal region andcontacting a distal section of the dummy implant against the sidewallsof the prepared distal region, contacting a proximal section of thedummy implant against the sidewalls of the prepared proximal region, andpositioning an intermediate section of the dummy implant along thenon-prepared middle region such that the intermediate section is spacedaway from the sidewalls of the non-prepared middle region; determining aposition of a femoral implant based on the dummy implant; subsequentlyremoving the dummy implant from the femoral canal; and after removingthe dummy implant, preparing the sidewalls of the middle region of thefemoral canal by creating a tapered shape along the middle regionbetween the prepared proximal and distal regions.
 11. The method ofclaim 10, further comprising applying a force to the dummy implant andretracting the femur away from the acetabulum and attaching anacetabular component to the acetabulum.
 12. The method of claim 10,further comprising accessing the femur using an anteriortrochanteric-based approach.
 13. The method of claim 10, furthercomprising preparing the distal region and the proximal region of thefemoral canal with a single tool that includes first and second cuttingsections that are separated by a non-cutting section.
 14. The method ofclaim 13, further comprising rotating the tool in a first direction andpreparing the distal region with the first cutting section, and rotatingthe tool in an opposing second direction and preparing the proximalregion with the second cutting section.
 15. The method of claim 13,further comprising sliding the second section of the tool that includesthe second cutting section over a first section that includes a firstcutting section.
 16. The method of claim 10, further comprising applyinga force to the dummy implant and using a cutting edge located along abottom of the plate and cutting a surface of the proximal femur and thegreater trochanter.
 17. A method of performing a hip replacementsurgical procedure, said method comprising: reaming sidewalls of adistal region of the femoral canal with a distal reamer without reamingsidewalls of a middle region or a proximal region of the femoral canal;reaming the sidewalls of the proximal region of the femoral canal with aproximal reamer without reaming the sidewalls of the middle region orthe distal region of the femoral canal; inserting a dummy implant intothe femoral canal, the dummy implant including a first section thatextends into and contacts the sidewalls of the proximal region, a secondsection that extends through the middle region and is spaced away fromthe sidewalls of the middle region, and a third section that extendsinto and contacts the sidewalls of the sidewalls of the distal region ofthe femoral canal; positioning a plate on the dummy implant over aproximal end of the femur; applying a force to the dummy implant andretracting the femur; attaching a measuring tool to the plate of thedummy implant and measuring a gap between the femur and the acetabulum;cutting the proximal end of the femur along the plate; removing thedummy implant from the femur; after removing the dummy implant, reamingthe sidewalls of the middle region of the femoral canal and tapering theshape between the proximal and distal regions.
 18. The method of claim17, wherein the distal reamer and the proximal reamer are included in asingle instrument.
 19. The method of claim 17, further comprisingaccessing the femur using an anterior trochanteric-based approach. 20.The method of claim 17, further comprising applying a force to the dummyimplant and cutting a surface of the proximal femur and the greatertrochanter with a cutting edge located along a bottom of the plate.